How to detect Noise in a Signal using Oscilloscope?

Say I have a noise free square wave signal of 1 khz frequency and 5 v amplitude. The signal passes through some optical receiver and the shape of the signal becomes slightly distorted with some noise in it. I have a digital oscilloscope that has FFT.

How can I use this FFT to detect the frequency of the noise so that I can separate the noise from the signal. I don't want to go through complex maths. Just tell me how to use the oscilloscope FFT function in determining the noise.

Any help would be highly appreciated. Thanks in advance. This Message was edited by: IndiJones on 2001-10-05 05:43 Reply With Quote View Profile 05-10-01 14:09 #2 borut Member level 1 Achievements: Join Date Sep 2001 Posts 36 Helped 0 / 0 Points 1,870 Level 10 This is very easy, you set the time-base in the mode that you see the noise so you have to "speed-up" the time-base and in this way you may "read" the frequency of the noise signal.

If the noise is constructed with many different ... more.

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